Radio frequency (RF) signals with a high frequency band used for audio/video transmission of a digital television are easily blocked by buildings or landform, and multipath interference may occur in transmission of the RF signals due to signal reflection. Therefore, in order to receive the RF signals with a relatively great quality, an antenna used for receiving the RF signals is usually set up outdoors and at a relatively high place. However, in this kind of setup, the antenna may be far from a media playing device (e.g., a digital television) that is used for playing media content carried by the RF signals. In addition, the antenna and the media playing device may be placed on different floors. As a result, it is hard to check immediately whether the placement of the antenna results in the best quality of the received RF signals.
In order to perform the checking, two persons need to cooperate with each other. One person watches the media played by the media playing device to determine the quality of the received RF signals, and guides the other person to adjust the placement of the antenna. However, this is inconvenient and time consuming. Further, the determination of the quality of the received RF signals is a subjective determination, and there is no objective standard to determine whether the placement of the antenna is optimal.
Another way to check immediately the placement of the antenna is to measure the RF signals using an instrument which can measure signal strength of the RF signals at a particular location and provide objective measurement result to a user, such that the user can adjust the antenna according to the measurement result. However, the measurement result of the signal strength is related to the RF signals received by the instrument, and thus, there may be a difference from the signal strength of the RF signals actually received by the antenna. Besides, the instrument displays a value to indicate the measurement result. Generally speaking, a greater value means greater signal strength. However, the RF signals having excessive signal strength may cause distortion of the media played by the media playing device, and ordinary people not skilled in the art is not knowledgeable in the appropriate range of the value.